1. Field of the Invention
The present invention relates to methods and apparatus for storing, reconstituting, dispensing and harvesting cell culture media for use in growing cells. More specifically, the present invention is a cell culture media containment system designed to allow users to reconstitute powdered cell culture media and then store the reconstituted media in a sterile condition until desired for use. The reconstructed cell culture media may then be dispensed from, and harvested into, the containment system.
2. Background Art
Cell culture media is typically a solution of amino acids, electrolytes, serum, serum fractions, vitamins, and growth factors. The constituents of cell culture media are combined in quantities to adjust the pH, osmolarity and other essential parameters for consistent, rapid cell growth therein.
Cell culture media provides an environment in which cells may exist and either develop within themselves a desired protein during growth or secrete the desired protein or other cellular product into the surrounding medium as a by-product of growth. Those cells that develop the desired protein within their structures must be chemically or mechanically fragmented in order to harvest the desired protein. More complex cells such as mammalian cells can produce sugar-modified cellular products and secrete the desired glycoprotein products into the cell culture medium for easy collection.
Cell culture medium is typically sold in either a liquid or a powdered form. The advantages to the liquid form are that sterile liquid cell culture media may be immediately introduced into the container in which the cells will grow. The disadvantage to liquid media, however, is that it is less stable during shipment and storage and, therefore, requires tighter inventory control. Typically, liquid media must also be stored in a refrigerated environment, and because of its relatively high weight when compared to powdered cell culture media, shipping is more expensive. Also, the shipping bags used in conveying liquid media must be strong enough to prevent leaks from occurring.
As liquid cell culture media is typically in a sterile condition when shipped, shipping bags must be strong enough to prevent any contamination or leakage from occurring. During shipping, the stresses produced by the liquid media contained with the bags can lead to leakage and contamination. Most bags utilize a construction whereby two sheets of a plastic material are joined by thermal or chemical bonding to form a single layer pillow-shaped bag having two longitudinal seams. The open ends of the cylinder are then sealed using known techniques and access apertures are formed through the bag wall through which liquid media may be introduced into the storage bag.
During shipping, and during subsequent storage or use, the longitudinal side seams of the storage bags are exposed to pressures both from within and from without the bag. Most leakage or contamination occurs from these seams.
As a result of the increased costs and risks involved in shipping and storing liquid cell culture media, users of larger quantities of cell culture media generally purchase the media in a powdered form. This powdered form requires less storage space, is easier to ship, and remains stable over a longer period of time.
Powdered media, however, necessitates the use of equipment to reconstitute the powdered media into a liquid form prior to introduction into the cell growth container. The equipment used to reconstitute the powdered media must be thoroughly cleaned and autoclaved between uses to obtain the sterility necessary to process the media prior to introduction into the cell growth container. This sterilization equipment is expensive, bulky, and difficult to maintain in a sterile condition.
Another disadvantage of powdered media is that, due to the exacting standards required of the end product, the reconstitution of the powdered media into a liquid form requires careful and meticulous preparation to ensure that the media constituents are added in the exact amount required. Factors such as spillage, airborne drift, retention of the powdered media within the container in which it is shipped, and other environmental or handling conditions can result in reconstituted cell culture media not falling within the required parameters for consistent rapid cell growth.
Powdered cell culture media is typically reconstituted by mixing powdered cell culture media and water for injection in a rigid container. During mixing, it is not uncommon for powdered cell culture media to become airborne and distributed throughout the environment surrounding the mixing area. Spillage may also occur.
After mixing of the water for injection and powdered cell culture media, the reconstituted cell culture media is then processed through sterilization equipment using any of the known sterilization techniques.
As reconstituted cell culture media must be in a sterile condition prior to introduction into the cell growth container, the sterilization process for reconstituted cell culture media is typically conducted as the last step prior to introduction of the media into the cell growth container or into sterile storage bags. Although verification of sterility may take some time, certain applications may rely on the sterilization process used and introduce the sterilized media into the cell growth container or bioreactor.
Sterilization is particularly important in cell culture media because the media is normally used to culture specific biological substances wherein the presence of unidentified, viable, biological organisms would lead to misleading, anomalous, or invalid results. One drawback to sterilization immediately prior to introduction of the cell culture media into the cell growth container is that the sterilization equipment must be located on-site. This equipment requires storage space and represents an investment in equipment which must be borne by each individual user.
After sterilization, the sterilized media is then stored in rigid drums or stainless steel barrels.
In light of the foregoing, therefore, there exists in the art a need for methods and apparatus for the storing and reconstituting of powdered cell culture media which simplify the difficult task of properly reconstituting the powdered media into a liquid form.
A further need exists in the art for methods and apparatus for storing and reconstituting powdered cell culture media which provide the advantages of the use of a powdered cell culture media while alleviating some of the need for expensive and complicated reconstitution and sterilization equipment.
Additionally, a need exits in the art for methods and apparatus for the reconstitution of powdered cell culture media which alleviate the risk of spillage and the task of cleaning after reconstitution.
Another need in the art is for methods and apparatus for the storing and reconstitution of powdered cell culture media which reduce the risk of contamination and reduce wasted materials due to improper preparation.
A further need exists in the art for methods and apparatus for the shipping and storing of powdered cell culture media which relieve the stresses imposed on the seams of the contaminant bag during shipping.
Still further, a need exists in the art for methods and apparatus for the shipping and storing of powdered cell culture media which alleviate the high shipping cost due to the shipment of the liquid components in a cell culture media.
An additional need exists in the art for methods and apparatus for the reconstitution of cell culture media which allows the mixing and storage of cell culture media to occur in less than two separate bags requiring separate support structures.
Another need exists in the art for methods and apparatus for the dispensing and harvesting of cell culture media which allows mixing, dispensing and harvesting to occur simultaneously in a system requiring only one support structure.